I am using a Raspberry Pi 2, a Roomba 400, and a logic level converter board in between. I seem to have my interface working properly. I receive data from the Roomba, and sending the 7 command resets it as it should. But the Roomba does not respond to any other command. For example, I believe that sending 128 and then 131 should put it in safe mode, which turns off the LED. But I get no response.I am entering these commands via python, with something like: